This complex story from the early days of psychoanalysis engrosses and even amuses as it unfolds through a series of conversations, treatment sessions and exchanged letters.

David Cronenberg’s career-long fascination with matters of the mind manifests itself in compelling but determinedly non-mind-bending fashion in “A Dangerous Method.” An elegant, coolly restrained account of the friendship between Sigmund Freud and Carl Jung, and its ultimate undoing by a brilliant female patient-student who came between them, this complex story from the early days of psychoanalysis engrosses and even amuses as it unfolds through a series of conversations, treatment sessions and exchanged letters. Still, the absence of gut-level impact and a talky approach to rarefied material mark it as one of Cronenberg’s more specialized entries, destined for a small but appreciative audience.

Scarcely a film one might have expected from the man who turned psychotherapy into a sick, bloody joke in 1979’s “The Brood,” “A Dangerous Method” will appeal less to Cronenberg’s body-horror contingent than to those who admire the cerebral bent that has always accompanied his love of splatter. Less concerned with the treatment of mental illness than with the way social norms encourage the suppression of human impulse, Christopher Hampton’s exceptionally coherent, literate script (adapted from his play “The Talking Cure” and John Kerr’s 1993 book “A Most Dangerous Method”) hinges on an unorthodox experiment Jung undertook with Sabina Spielrein, a Russian Jewish woman whom he treated for hysteria, and who later became a significant psychoanalyst in her own right.

First seen arriving at Jung’s Burgholzli Clinic in Zurich in 1904, Sabina (Keira Knightley) is a feral, convulsive wreck, though the film tastefully avoids depicting the obsession with defecation and masturbation that are among her more pronounced symptoms. A young doctor in his early 30s, Jung (Michael Fassbender) is just beginning to test his hero Freud’s revolutionary methods and achieves considerable success in the case of Sabina, who quickly reveals her intelligence and emotional warmth.

Two years later, Jung travels to Vienna to meet Freud (Viggo Mortensen), initiating a close but often uneasy bond with unexpected consequences when Freud asks him to treat a fellow psychiatrist, Otto Gross (Vincent Cassel). Unruly, defiant and disdainful of anything he perceives as a repressive social constraint, Otto encourages Jung to cross the lines of acceptable practice. Conveniently enough, Sabina, eager for healthy sexual experience, has given Jung an open invitation, one he is unable to resist for long despite his loyalty to his wife, Emma (Sarah Gadon), and their young children.

An illicit affair begins, dramatized with period-appropriate discretion plus a few intense bouts of spanking. Surprisingly, this aspect of the picture generates little in the way of scandalous heat, largely because Jung seems more invested in the scientific implications of the relationship than in the emotional or ethical ones. Methodical the film may be, but an element of real danger does seem crucially missing.

The film is far more riveting when it focuses on Freud and Jung, distilling the clash between these two equally imposing but very different minds into a series of crisp, intensely concentrated dialogues. While Jung grows impatient with Freud’s insistence that a sexual component underlies every neurosis, Freud fears Jung will discredit the cause of psychoanalysis by pushing past empirical boundaries. A decisive split occurs when Sabina, stinging from Jung’s rejection, continues her treatment and her medical studies under Freud.

Even as the story settles into an epistolary structure, it seems to run along an unbroken current of ideas, and the two male leads bring a bone-dry wit to this battle of wills and egos. Signaling both intelligence and naivete from behind his spectacles, Fassbender makes Jung a highly suggestible figure prone to blurring the lines between doctor and patient. And Mortensen’s Freud, a sardonic, ineffably sinister presence who rarely raises his voice above a silky-smooth purr, calmly steals the picture; following the thesp’s terrific work in “A History of Violence” and “Eastern Promises,” his third collaboration with Cronenberg has resulted in something no less distinctive.

Rather less assured, and initially the film’s most problematic element, is Knightley, whose brave but unskilled depiction of hysteria at times leaves itself open to easy laughs. The spectacle of the usually refined actress flailing about, taking on a grotesque underbite, and stammering and wailing in a Russian accent is perhaps intended to clash with her co-stars’ impeccable restraint, but does so here in unintended ways. But as Sabina’s condition improves, so does Knightley’s performance, eventually registering the mix of tenderness and tenacity that presumably made Spielrein such a force in her mentors’ lives.

Maintaining a cool body temperature throughout, “A Dangerous Method” shows extreme attentiveness to the subtler peculiarities of its strange story: the way Sabina’s illness frees her to slip the bonds of a patriarchal society in a way Emma cannot, for instance, or Jung and Sabina’s shared enthusiasm for Wagner, which causes Freud understandable and amusing consternation even as it beckons toward the encroaching shadow of WWI.

Precision defines every aspect of the production, from the immaculate lensing and editing to Howard Shore’s memorable score and James McAteer’s production design, which fastidiously re-creates everything from the specific minutiae of Freud’s office to the intricate instruments Jung uses during a word-association experiment. Scenic shots of Vienna and Germany’s Lake Constance add further luster to the film’s look.

A Dangerous Method

Canada-Germany

Production

A Sony Pictures Classics (in U.S.) release of a Jeremy Thomas presentation of a Lago Film, Prospero Pictures and Recorded Picture Co. co-production in association with Millbrook Pictures. (International sales: HanWay Films, London.) Produced by Thomas. Executive producers, Thomas Sterchi, Matthias Zimmerman, Karl Spoerri, Stephan Mallmann, Peter Watson. Co-producers, Marco Mehlitz, Martin Katz. Directed by David Cronenberg. Screenplay, Christopher Hampton, based on the stage play "The Talking Cure" by Hampton and the book "A Most Dangerous Method" by John Kerr.